Net zero development: Which way to run the streets

Net zero development: Which way to run the streets

Written by: Jake Evans

Which way do you run the streets to maximize solar exposure for dense Net Zero development?

A street view of a row of colorful houses. The center blue house is a Net Zero house designed by Powerhouse Designs and built by TC Legend Homes.

Common wisdom states that the optimal streets run east west, which makes sense if you’re the house on the north side of the street, because there’s nothing shading your house, garden or solar panels. However, living on the south side of the street, you suffer from north facing gardens and probably some shading unless the lots are 5000sf or greater.

Critically, 10 dwelling units (du) per acre is the density with enough inhabitants to support a bus service (*1), a key part of the sustainable urbanist vision for transit, pedestrian & bike use, rather than private cars. An acre is 43500sf.

My conclusion is that the common wisdom is wrong for dense, Net Zero development, that the streets should run north-south.

A Net-Zero house has most of the windows on the south side of the house because south facing windows can be effectively shaded from summertime overheating, and can harvest wintertime solar energy.

Because all the windows are on the south walls, we can’t have another 2-story house immediately to the south as shown in ‘East-West 3700’ below, or the valuable direct wintertime sunlight will be prevented from entering & you’ll have a house that is gloomy all winter.

Sure, if the lots are big, we can keep the southern house away, as shown in ‘East-West 4500’ below, but then we end up with less than 10 du/ acre (du/a) and there’s no bus & everyone’s driving cars.

The ‘North-South 3800’ drawing below shows a 1-story neighbor garage to the south, avoiding shade. Bingo! That’s a 3800sf lot, and offers 11.34 du/a. Additionally the frontage length is reduced which lowers roadway & utility development costs.

Street Orientation Option 1 North-South 3800. A drawing showing a block of houses on streets oriented north to south and situated on their lots with garages on the north side and the long side of the house on the north and south side, allowing solar gain on the south side while not being blocked by the roofline of the neighboring house. Text says "2000 sf house with dbl garage. 3835 sf lot. 59' frontage / du = 11.34, du/a = density supports bus OK. Winter light = 100%. Equal solar exposure for all houses."
Street Orientation Option 2 East-West 3700. A drawing showing a block of houses on streets oriented east to west and situated on their lots with garages to one side of the house and the long side of the house on the north and south side. The two houses to the north of the block have garages on the west side and the southern two houses have garages on the east side mimicking the layout. The orientation allows solar gain on the south side but the diagram shows that 40% of the northern houses will be blocked by the roofline of the neighboring southern house. Text says "2000 sf house with dbl garage. 3700 sf lot. 74' frontage / du = 11.76, du/a = density supports bus OK. Winter light = 60% @ northern houses."
Street Orientation Option 3 East-West 4500. A drawing showing a block of houses on streets oriented east to west and situated on their lots with garages to one side of the house and the long side of the house on the north and south side. The two houses to the north of the block have garages on the west side and the southern two houses have garages on the east side mimicking the layout. The orientation allows solar gain on the south side while not being blocked by the roofline of the neighboring southern house. However the houses are visibly farther apart. Text says "2000 sf house with dbl garage. 4505 sf lot. 74' frontage / du = 9.66, du/a = density ~ supports bus OK. Winter light = 100%."

(*1) Transit modes related to residential density (Boris Pushkarev & Jeffry M Zupan)

Impact of Eco-Conscious Living Series: Water Efficiency

Impact of Eco-Conscious Living Series: Water Efficiency

Written by: Nicole Miller

Water Efficiency

Water is often thought of as an infinite resource because of the vastness of the oceans, lakes and rivers and the great quantities of rainfall across the land.

In actuality, of all the water on this planet, less than 0.3% of it is accessible for human consumption.2 Of that 0.3% of accessible water, many regions are battling pollution in their local tap water, as well as water shortages.

In fact, in a 2014 study by the U.S. Government Accountability Office, “40 of 50 state water managers expected shortages in some portion of their states under average conditions in the next 10 years”1.

This is a reality that we are seeing ring true 8 years later.

Groundwater in the USA is the main source of drinking water for almost 50% of the total population and “provides over 50 billion gallons per day for agricultural needs.”4 However, as shown in Figure 1 and described by USGS in “Groundwater Decline and Depletion,” many of the USA’s largest aquifers are depleting due to the outweighed removal of water from natural replenishing4.

1 “Map of the United States (excluding Alaska) showing cumulative groundwater depletion, 1900 through 2008, in 40 assessed aquifer systems or subareas….Colors are hatched in the Dakota aquifer (area 39) where the aquifer overlaps with other aquifers having different values of depletion.”4

Although, this is not just an issue with large aquifers and the ramifications on one side of the country will inevitably affect the country as a whole, as we share resources throughout from bottled water to crops and livestock watered with local aquifers.  Not to mention, as we deplete our own resources, we are simultaneously depleting the resources for our surrounding ecosystems, which require clean water just as we do.

As with all environmental issues, there is a trickle-down effect that must be taken into consideration.

But as a society or individual, what can we do to help?

Firstly, if your local tap water is safe to drink, then choose that option before purchasing bottled water and taking away the local tap water from others. You can also install a whole-house water filter if worried about certain pollutants in the local tap water.

Secondly, opt to use a dishwasher and heated dry option instead of handwashing your dishes where applicable.3 Unless you are correctly hand washing dishes in a two-basin setup as described in Porras, Gabriela Y, et al article, it is more efficient in both greenhouse gas emissions and water usage, to use a dishwasher (with the only pre-treatment being scraping off food particles).3

Thirdly, when purchasing appliances and plumbing fixtures, only purchase those that are WaterSense® labelled. This ensures they are water efficient. Also opt for dual flush toilets if composting toilets are not an option.

Fourth, do not plant grass for landscaping and instead plant native flora that doesn’t require extra watering. If some form of grass is desired, try planting an alternative like wildflowers, clover, moss or sedum. These can give a similar visual and functional effect as grass but promote a more biodiverse ecosystem while also requiring little to no manual watering.

Lastly, if you do choose a landscape that requires manual watering, install a rain catchment system to supply the water instead of using potable water out of the hose bib. There is no reason to use clean drinking water on plants and lawns, when they will fair just fine with rainwater.

There are many other ways to increase water efficiency and reduce water consumption, however these listed are some of the easiest and best ways that you can make a difference just in your home.

At TC Legend Homes we understand the importance of water conservation through efficiency, which is why we have made it our standard to require WaterSense® labelled fixtures. We also encourage clients to landscape with only native flora and add rain catchment systems to their yard.

In actively reducing our water consumption and using water efficient solutions, we can help reduce the rate at which we are depleting the world’s accessible water, leaving more time to find a solution to the water crisis and help reverse the impact we’ve already had.

This in turn, will also reduce the impact that our water depletion is having on the ecosystems around us, as well as help reduce the inequity that comes with competition for draining resources.


“Freshwater: Supply Concerns Continue, and Uncertainties Complicate Planning.” GAO, U.S. Government Accountability Office, 2/21/22.

2 Kimberly Mullen. “Information on Earth’s Water.” NGWA, National Ground Water Association, 2/21/22.

3Porras, Gabriela Y, et al. “A Guide to Household Manual and Machine Dishwashing through a Life Cycle Perspective.” Environmental Research Communications, vol. 2, no. 2, 12 Feb. 2020.

4Water Science School. “Groundwater Decline and Depletion.” USGS, United States Geologic Survey, 2/21/22.

New! SIPs & ICF Install Training Opportunity!

New! SIPs & ICF Install Training Opportunity!

TC Legend is pleased to announce we will train SIPs installers & ICF installers this summer through winter!

Training will take place at our sites in and around Bellingham, WA.

Places are limited as we only have six houses left to build this year and four of them have foundations poured already, none have the SIPs erected. So be quick to claim your spot!

Folks who are interested should have a minimum of (2) years framing experience for SIPs, and (2) years concrete foundation work experience for ICF.

The purpose of these trainings is to increase the number of capable SIPs & ICF installers.

TC Legend has a growing plans-for-sale business which will design & permit many new houses in the Pacific Northwest, and these plans (with permits) could be built by the newly trained installers.

Cost for the training will be $175/ day.

SIPS Training: (4) days for SIPs (3 days of walls, 1 of roof).

ICF Training: (3) days for ICF.

We encourage established contractors to contact us!

Please contact Nicole for more info on training dates and to claim your spot:

TC Legend Typical House

TC Legend Typical House

Ted & Jake did some virtual conference speaking last summer.

The subject was how to build an affordable Net Zero home. The Built Green footage is here: ­­­­­Videos | TC Legend Homes,  and the NW Eco Build footage should be along shortly.

The principles are simple. Here are the notes:


Simple, rectangular footprint, Conforming to the formula for the Pacific Northwest the rectangular footprint is; 1.6 units long on south wall, 1 unit deep east and west walls. No wiggles or bump-outs as they increase cost and reduce energy efficiency. The long side faces south to harvest winter passive solar heat. Short east and west sides are minimized to reduce exposure to hot, low angle sun.

Formula for glazing. To avoid overheating during summer, large east and west facing widows are avoided. South-side glazing is heavily preferred as there we can shade the hot, high summertime sun with eaves and shades, yet allow the low wintertime solar heat to enter.

Daylighting. Rooms needing great daylight: kitchen, dining room, etc. are located on the south side behind the plentiful south windows.

The low-light-requirement rooms: mechanical rooms, bathrooms, staircases etc. are to the north.

Correctly sized clerestory windows can bring daylight deep within the interior of the house.

Pitched roof. A huge south roof, pitching to the south collects solar power from roof-mounted PV panels. Often the south roof is asymmetrically large, to create space for the maximum number of PV panels, achieving Net Positive and powering an electric car. This is a new aesthetic – Environmental Modernism!

Right sized rooms: Interior spaces and rooms that are exactly big enough to thrive within, but no bigger. Well placed exterior doors access the outside when you need more space.

Energy modeling. Modeling the building during the design process ensures it’s on-track to meet Net Zero, and allows precise evaluation of the cost/ energy advantages of the various construction components, including the HRV.

We use the WSU component performance worksheet. It’s a free excel spreadsheet, specific to WA state.

Detail: Post & beam structure.  Fine-finished structural posts and beams enrich the interior at low cost, and allow easy remodel as no interior walls are loadbearing.

Detail: Slab-on grade. Fine finishing the concrete slab-on-grade floor gives a modern, durable interior at low cost. Not compulsory though, the slab can be covered with engineered floating floors.

Site selection

Flat lot: Lower construction costs by avoiding steep lots with expensive retaining walls, excavation, soils trucking and geotechnical involvement.

Utilities: Power, water, sanitary drainage/ septic, driveways. Utilities can cost over $80K to install on remote rural lots. The ideal lot has all the utilities stubbed-out in the street or on-site.

Solar exposure: An ideal site would have a clear sky to the south, down to the horizon so the building can harvest low, wintertime passive solar heat. If there were deciduous trees to the east and west, those trees could shade the east and west walls / windows in summertime but allow valuable winter light to penetrate once the leaves have all fallen off!

Critical Areas: Water in all forms is heavily protected in Washington State. The presence of wetlands, streams, lakes and ocean all add to the complexity and cost to build.


SIPs panel construction: Highly insulated R29 walls, R49 roof are fast to build and are inherently very air-tight. The thick roof panels span far and make vaulted roof space as standard.

ICF formed stemwalls: Insulating the stem-walls adds R24 below grade, preventing the building from leaking heat at the slab edge.

4” under-slab foam: R20 foam below the slab as standard.

Triple Pane windows: Standard.


Heat recovery ventilator (HRV): Delivering fresh air is essential in super-sealed modern buildings. HRV ventilators recover over 90% of outgoing heat, whist providing constant fresh exterior air, filtered to HEPA standards with particulates removed.

Heat pump. Electric air-to-air (Fujitsu), or air-to-water (Chilltrix) heatpumps are highly efficient and provide cold air conditioning in addition to heating.

Concrete floor: The slab-on grade is inside the energy shell (above the 4” R20 foam) and serves as a thermal heatsink; storing the house’s warmth, or cool, within the concrete. Protecting the heatpump from short-cycling and preventing temperature swings, even during a multi-day power-outage.

Energy star appliances: As standard.

Solar panels: As standard to achieve net zero, or net positive if an electric car will be driven.

How $200/ square foot?

The economics are made possible because the house is explicitly designed to achieve net zero and to cost $200/sf. The shell, mechanicals and living quality are best-of-breed, the finishes are durable, solid materials, and modest.

There is an economical point (~1200sf) where the house has to become two story to remain in this cost bracket.

Small houses below 1500sf cost closer to $250/ sf as the basic elements (heating, kitchen, bathroom, etc.) all still have to be present and are not reduced as the floorplan reduces.

$200/ sf is possible (for a NetZero house with solar installed) with a 2,000sf house.

If you want a small (e.g. 800sf) NetZero house for $200/ sf: Think about duplexing with your friends, triplex, multiplex! Co-housing……..

zero energy plans